1. Field of the Invention
This invention relates to a method of preparing a laboratory standard material and, more particularly, to a method of preparing blood serum reference compositions of the type described in U.S. Pat. No. 3,876,375 (hereinafter referred to as the Maurukas patent), the Maurukas patent being incorporated herein by this reference.
2. Description of the Prior Art
The Maurukas patent discloses a biological composition for use as a reference control in diagnostic analysis. The Maurukas composition comprises, in its nonbiological component, from about 60 to about 80 weight percent water, from about 20 to about 40 weight percent of at least one alkylene polyol having from 2 to 5 carbon atoms, the remainder being chiefly at least one natural biological material selected from a group consisting of blood serum, enzymes, metabolites, electrolytes, and hormones. However, the method disclosed in the Maurukas patent for producing such a biological composition is commercially impractical. For example, Maurukas employed human blood serum obtained from a clinical laboratory. This source of human blood serum is impractical for use on a commercial scale. The method described in the Maurukas patent begins with human blood serum obtained from clinical laboratories. While such sources may be tapped for small quantities of human blood serum, there are far too few such sources to provide the large quantities of human blood needed in the commercial manufacture of reference controls. In fact, citrated plasma, rather than human blood serum is the only viable source for obtaining enough human blood necessary for commercial production. Citrated plasma comes from plasma pheresis blood donor banks which specialize in selling citrated plasma. Citrated plasma is obtained from donors via plasma pheresis at a rate of one liter per week per donor and also has the additional advantage over clinical laboratory pooled human blood in that it is checked for hepatitis and venereal disease. Further, the method disclosed by the Maurukas patent for processing human blood serum entails the loss of substantial quantities of protein. The Maurukas process entails freezing a block of pool blood serum and then slowly thawing the frozen block at a controlled temperature over a 3 to 7 day period to obtain a desired volume of concentrated protein. Over 25% of the protein is left behind in the frozen matrix discarded via Maurukas' above process.